DSpace Collection:http://hdl.handle.net/2117/659
Tue, 31 Mar 2015 22:06:47 GMT2015-03-31T22:06:47Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoBeamforming antennas for 60 GHz positioning systemshttp://hdl.handle.net/2117/26948
Title: Beamforming antennas for 60 GHz positioning systems
Authors: Toda, Annapapió; Romeu Robert, Jordi; Jofre Roca, Lluís; de Flaviis, Franco
Abstract: In this paper we analyze the benefit of using phased arrays as the receiving antennas of indoor location systems. A 60 GHz code division multiple access carrier-based ultra-wide band positioning system for the simultaneous location of diverse markers is considered. The positioning error in an indoor environment is assessed when omnidirectional antennas are used at the receiving sensors and when they are substituted by beamforming antennas. Results show that beamforming systems can effectively mitigate the multipath effects and achieve positioning accuracies close to those achievable in free space scenarios. The performance of omnidirectional systems is severely degraded by multipath and multiple access interference.Mon, 23 Mar 2015 14:15:57 GMThttp://hdl.handle.net/2117/269482015-03-23T14:15:57ZToda, Annapapió; Romeu Robert, Jordi; Jofre Roca, Lluís; de Flaviis, Francono60 GHz, Beamforming antennas, Location system, Millimeter wave, Positioning systemIn this paper we analyze the benefit of using phased arrays as the receiving antennas of indoor location systems. A 60 GHz code division multiple access carrier-based ultra-wide band positioning system for the simultaneous location of diverse markers is considered. The positioning error in an indoor environment is assessed when omnidirectional antennas are used at the receiving sensors and when they are substituted by beamforming antennas. Results show that beamforming systems can effectively mitigate the multipath effects and achieve positioning accuracies close to those achievable in free space scenarios. The performance of omnidirectional systems is severely degraded by multipath and multiple access interference.Regularization of the 2D TE-EFIE for homogeneous objects discretized by the Method of Moments with discontinuous basis functionshttp://hdl.handle.net/2117/25527
Title: Regularization of the 2D TE-EFIE for homogeneous objects discretized by the Method of Moments with discontinuous basis functions
Authors: Sekulic, Ivan; Úbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, Alexander
Abstract: The discretization of the Electric-Field Integral Equation (EFIE) by the Method of Moments (MoM) for a transversal electric (TE) illuminating wave impinging on an infinitely long cylinder (2D-object) is traditionally carried out with continuous piecewise linear basis functions. In this paper, we present a novel discretization of the TE-EFIE formulation for the scattering analysis of homogeneous, perfectly conducting 2D-objects based on the expansion of the currents around the line-boundary through discontinuous piecewise linear or piecewise constant basis functions. We show for several infinitely long cylinders, with smooth or sharp-edged sections, the good accuracy of the proposed approach in the computation of far-field and near-field quantities, such as RCS and currents, with respect to the observed accuracy in conventional continuous piecewise linear discretizations.Wed, 14 Jan 2015 17:52:55 GMThttp://hdl.handle.net/2117/255272015-01-14T17:52:55ZSekulic, Ivan; Úbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, AlexandernoBasis functions, Homogeneous objectsThe discretization of the Electric-Field Integral Equation (EFIE) by the Method of Moments (MoM) for a transversal electric (TE) illuminating wave impinging on an infinitely long cylinder (2D-object) is traditionally carried out with continuous piecewise linear basis functions. In this paper, we present a novel discretization of the TE-EFIE formulation for the scattering analysis of homogeneous, perfectly conducting 2D-objects based on the expansion of the currents around the line-boundary through discontinuous piecewise linear or piecewise constant basis functions. We show for several infinitely long cylinders, with smooth or sharp-edged sections, the good accuracy of the proposed approach in the computation of far-field and near-field quantities, such as RCS and currents, with respect to the observed accuracy in conventional continuous piecewise linear discretizations.Increased dynamic range for RFID EM-field measurementshttp://hdl.handle.net/2117/25070
Title: Increased dynamic range for RFID EM-field measurements
Authors: Capdevila Cascante, Santiago; Romeu Robert, Jordi; Jofre Roca, Lluís; Bolomey, Jean Charles
Abstract: This paper presents a new methodology to measure the electromagnetic (EM) field using RFID tags, overcoming the limitations in dynamic range arisen by the conventional excitation of RFID tags. The methodology consists in the use of two different signals when interrogating the RFID tag. The first signal is in charge of powering up and triggering the response of the RFID tag, while the second one, with lower power, performs the EM-field measurement. With this approach the dynamic range of the EM-field measurement is increased up to the sensitivity of the receiver, and additionally the non-linearities in the measured field distribution are completely removed.Wed, 17 Dec 2014 16:17:28 GMThttp://hdl.handle.net/2117/250702014-12-17T16:17:28ZCapdevila Cascante, Santiago; Romeu Robert, Jordi; Jofre Roca, Lluís; Bolomey, Jean CharlesnoDynamic range, Field measurementThis paper presents a new methodology to measure the electromagnetic (EM) field using RFID tags, overcoming the limitations in dynamic range arisen by the conventional excitation of RFID tags. The methodology consists in the use of two different signals when interrogating the RFID tag. The first signal is in charge of powering up and triggering the response of the RFID tag, while the second one, with lower power, performs the EM-field measurement. With this approach the dynamic range of the EM-field measurement is increased up to the sensitivity of the receiver, and additionally the non-linearities in the measured field distribution are completely removed.Design and performance evaluation of a dielectric flat lens for millimeter-wave applicationshttp://hdl.handle.net/2117/25067
Title: Design and performance evaluation of a dielectric flat lens for millimeter-wave applications
Authors: Imbert Villà, Marc; Papió, Anna; de Flaviis, Franco; Jofre Roca, Lluís; Romeu Robert, Jordi
Abstract: In this paper, a practical fabrication of a dielectric flat lens for millimeter-wave applications is presented. A previous theoretical dielectric flat lens antenna design, consisting of a set of concentric rings with different permittivity values for each, is now modeled and analyzed for a practical prototype fabrication and preliminary performance evaluation at 75 GHz. Preliminary measurements show that with the dielectric flat lens antenna prototype we can achieve beam-steering capabilities from -30 to +30 with around 17 dB of gain, and up to ±45 beam-steering capabilities with around 15 dB of gain, with low side-lobe levels. This design also leads to a low-profile antenna configuration, easy to manufacture and low-cost, in order to integrate the whole structure in a compact millimeter-wave commercial wireless system.Wed, 17 Dec 2014 15:53:36 GMThttp://hdl.handle.net/2117/250672014-12-17T15:53:36ZImbert Villà, Marc; Papió, Anna; de Flaviis, Franco; Jofre Roca, Lluís; Romeu Robert, JordinoDielectric flat lens antenna, Millimeter-wave applications, Near-field to far-field measurementsIn this paper, a practical fabrication of a dielectric flat lens for millimeter-wave applications is presented. A previous theoretical dielectric flat lens antenna design, consisting of a set of concentric rings with different permittivity values for each, is now modeled and analyzed for a practical prototype fabrication and preliminary performance evaluation at 75 GHz. Preliminary measurements show that with the dielectric flat lens antenna prototype we can achieve beam-steering capabilities from -30 to +30 with around 17 dB of gain, and up to ±45 beam-steering capabilities with around 15 dB of gain, with low side-lobe levels. This design also leads to a low-profile antenna configuration, easy to manufacture and low-cost, in order to integrate the whole structure in a compact millimeter-wave commercial wireless system.Ku-band flat lens design for satellite TV applicationshttp://hdl.handle.net/2117/24724
Title: Ku-band flat lens design for satellite TV applications
Authors: Imbert Villà, Marc; Romeu Robert, Jordi; Jofre Roca, Lluís; Papió, Anna; de Flaviis, Franco
Abstract: In this paper, the design of a dielectric flat lens to operate in the Ku-band for satellite communications is presented. Modern dishes intended for home television are generally bulky and heavy. Moreover, the costs of installation and alignment with the desired satellite are high. Satellite television providers are therefore looking for alternatives to the traditional dishes that could provide narrow beamwidths (5° max.), high gains, low side-lobe levels and beam steering capabilities. To satisfy the aforementioned requirements, we propose a dielectric flat lens to steer and enhance the radiation of the feed in a particular direction. Our simulation results indicate that we can achieve up to 31 dB of gain with 2.3° beamwidth, and beam-steering capabilities from +15° to -15° in both azimuth and elevation with more than 28 dB of gain with around 4° beamwidth, with low side-lobe levels, in the entire frequency band of interest (from 11.7 to 12.2 GHz). Moreover, the proposed design leads to a low-profile antenna configuration, easy to manufacture and low-cost.Thu, 13 Nov 2014 17:15:25 GMThttp://hdl.handle.net/2117/247242014-11-13T17:15:25ZImbert Villà, Marc; Romeu Robert, Jordi; Jofre Roca, Lluís; Papió, Anna; de Flaviis, FranconoBeam steering, Dielectric materials, Direct broadcasting by satellite, Lens antennas, Satellite antennas, Television broadcasting, Ku-band flat lens, Antenna configuration, Beam steering capabilities, Dielectric flat lens, Frequency 11.7 GHz to 12.2 GHz, Home television, Satellite TV applications, Satellite communicationsIn this paper, the design of a dielectric flat lens to operate in the Ku-band for satellite communications is presented. Modern dishes intended for home television are generally bulky and heavy. Moreover, the costs of installation and alignment with the desired satellite are high. Satellite television providers are therefore looking for alternatives to the traditional dishes that could provide narrow beamwidths (5° max.), high gains, low side-lobe levels and beam steering capabilities. To satisfy the aforementioned requirements, we propose a dielectric flat lens to steer and enhance the radiation of the feed in a particular direction. Our simulation results indicate that we can achieve up to 31 dB of gain with 2.3° beamwidth, and beam-steering capabilities from +15° to -15° in both azimuth and elevation with more than 28 dB of gain with around 4° beamwidth, with low side-lobe levels, in the entire frequency band of interest (from 11.7 to 12.2 GHz). Moreover, the proposed design leads to a low-profile antenna configuration, easy to manufacture and low-cost.Switched-beam antenna array for 60 GHz WPAN applicationshttp://hdl.handle.net/2117/24723
Title: Switched-beam antenna array for 60 GHz WPAN applications
Authors: Imbert Villà, Marc; Romeu Robert, Jordi; Jofre Roca, Lluís; Papió, Anna; de Flaviis, Franco
Abstract: In this paper, the design of a switched-beam antenna array to operate in the 60 GHz band for short-range WPAN applications is presented. In order to overcome the high path-loss attenuation at millimeter-wave frequencies and, moreover, to achieve high data rate wireless communications, highly directive antennas are required. In addition, beam-steering antennas are also needed to deal with the high user random mobility and human-body shadowing characteristic of indoor environments. For these reasons, we propose a design based on a five by five slot antenna array, in which each single element can be selected individually, and a dielectric flat lens to steer and enhance the radiation in a particular direction. A total of 25 fixed high-gain beams can be selected individually to scan in both theta and phi directions. Our simulation results indicate that we can achieve up to 18.4 dB of gain, and beam-steering capabilities from +30° to -30° with more than 15 dB of gain, and up to ±45° with around 14 dB, with low-side lobe levels, in the entire frequency band of interest (from 57 to 64 GHz).Thu, 13 Nov 2014 15:44:11 GMThttp://hdl.handle.net/2117/247232014-11-13T15:44:11ZImbert Villà, Marc; Romeu Robert, Jordi; Jofre Roca, Lluís; Papió, Anna; de Flaviis, FranconoIn this paper, the design of a switched-beam antenna array to operate in the 60 GHz band for short-range WPAN applications is presented. In order to overcome the high path-loss attenuation at millimeter-wave frequencies and, moreover, to achieve high data rate wireless communications, highly directive antennas are required. In addition, beam-steering antennas are also needed to deal with the high user random mobility and human-body shadowing characteristic of indoor environments. For these reasons, we propose a design based on a five by five slot antenna array, in which each single element can be selected individually, and a dielectric flat lens to steer and enhance the radiation in a particular direction. A total of 25 fixed high-gain beams can be selected individually to scan in both theta and phi directions. Our simulation results indicate that we can achieve up to 18.4 dB of gain, and beam-steering capabilities from +30° to -30° with more than 15 dB of gain, and up to ±45° with around 14 dB, with low-side lobe levels, in the entire frequency band of interest (from 57 to 64 GHz).Nonconforming discretization of the Magnetic-Field Integral Equation with volumetric testinghttp://hdl.handle.net/2117/24721
Title: Nonconforming discretization of the Magnetic-Field Integral Equation with volumetric testing
Authors: Úbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, Alexander
Abstract: The RWG-discretization in Method of Moments (MoM) of the Magnetic-Field and Electric-Field Integral Equations (MFIE, EFIE) show evident discrepancy in the computed RCS, especially for small objects with edges and corners. The nonconforming monopolar-RWG discretization of the MFIE exhibits a smaller a deviation with respect to the EFIE. The Combined-Field Integral Equation (CFIE), which arises from the combination of the EFIE and the MFIE, is very often implemented with the RWG basis functions, whereby some accuracy with respect to EFIE is lost too. In this paper, we present a new nonconforming monopolar-RWG discretization of the MFIE, based on testing the magnetic field over small tetrahedral elements attached to the surface, inside the body under analysis. This formulation is compatible with a successful nonconforming discretization of the EFIE with the monopolar-RWG expansion of the current and volumetric testing. This allows the development of a nonconforming discretization of the CFIE.Thu, 13 Nov 2014 15:34:59 GMThttp://hdl.handle.net/2117/247212014-11-13T15:34:59ZÚbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, AlexandernoThe RWG-discretization in Method of Moments (MoM) of the Magnetic-Field and Electric-Field Integral Equations (MFIE, EFIE) show evident discrepancy in the computed RCS, especially for small objects with edges and corners. The nonconforming monopolar-RWG discretization of the MFIE exhibits a smaller a deviation with respect to the EFIE. The Combined-Field Integral Equation (CFIE), which arises from the combination of the EFIE and the MFIE, is very often implemented with the RWG basis functions, whereby some accuracy with respect to EFIE is lost too. In this paper, we present a new nonconforming monopolar-RWG discretization of the MFIE, based on testing the magnetic field over small tetrahedral elements attached to the surface, inside the body under analysis. This formulation is compatible with a successful nonconforming discretization of the EFIE with the monopolar-RWG expansion of the current and volumetric testing. This allows the development of a nonconforming discretization of the CFIE.Volumetric testing with wedges for a nonconforming discretization of the Electric-Field Integral Equationhttp://hdl.handle.net/2117/24720
Title: Volumetric testing with wedges for a nonconforming discretization of the Electric-Field Integral Equation
Authors: Úbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, Alexander
Abstract: The discretization in Method of Moments (MoM) of the Electric-Field Integral Equation (EFIE) is traditionally carried out with divergence-conforming sets of basis functions, like the RWG set. This enforces the normal continuity of the current across the edges arising from the discretization and makes the quasi-singular Kernel contributions numerically manageable. However, these MoM-implementations of the EFIE show little flexibility when handling nonconformal meshes, normally arising from from the juxtaposition or interconnection of independent meshes in the modular design of composite objects. A nonconforming discretization of the EFIE is possible if the testing procedure is carried out over volumetric elements attached to the surface triangulation, inside the body. In this paper, we present a new nonconforming discretization of the EFIE, where wedges attached to the source triangles are used as testing volumetric elements.Thu, 13 Nov 2014 15:30:46 GMThttp://hdl.handle.net/2117/247202014-11-13T15:30:46ZÚbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, AlexandernoThe discretization in Method of Moments (MoM) of the Electric-Field Integral Equation (EFIE) is traditionally carried out with divergence-conforming sets of basis functions, like the RWG set. This enforces the normal continuity of the current across the edges arising from the discretization and makes the quasi-singular Kernel contributions numerically manageable. However, these MoM-implementations of the EFIE show little flexibility when handling nonconformal meshes, normally arising from from the juxtaposition or interconnection of independent meshes in the modular design of composite objects. A nonconforming discretization of the EFIE is possible if the testing procedure is carried out over volumetric elements attached to the surface triangulation, inside the body. In this paper, we present a new nonconforming discretization of the EFIE, where wedges attached to the source triangles are used as testing volumetric elements.RF monitoring of commercial vascular stents with dipole scattering resonanceshttp://hdl.handle.net/2117/24702
Title: RF monitoring of commercial vascular stents with dipole scattering resonances
Authors: Arauz Garofalo, Gianluca; López Domínguez, Víctor; Hernández Ferras, Joan Manel; Rodríguez Leor, Oriol; Bayés Genis, Antoni; Rius Casals, Juan Manuel; O'Callaghan Castellà, Juan Manuel; García Santiago, Antoni; Tejada Palacios, Javier
Abstract: We have compared measurements and simulations of the microwave forward scattering of several commercial coronary stents. We immerse the stents in water to replicate the permittivity of biological tissues and find that their dipole scattering resonances can be detected at frequencies close to 300 MHz even though the stents are not purposely designed to facilitate such detection. We discuss how stent resonances can be used to monitor restenosis with non-invasive and non-ionizing techniques.Wed, 12 Nov 2014 14:35:01 GMThttp://hdl.handle.net/2117/247022014-11-12T14:35:01ZArauz Garofalo, Gianluca; López Domínguez, Víctor; Hernández Ferras, Joan Manel; Rodríguez Leor, Oriol; Bayés Genis, Antoni; Rius Casals, Juan Manuel; O'Callaghan Castellà, Juan Manuel; García Santiago, Antoni; Tejada Palacios, JaviernoMonitoring, Restenosis, StentWe have compared measurements and simulations of the microwave forward scattering of several commercial coronary stents. We immerse the stents in water to replicate the permittivity of biological tissues and find that their dipole scattering resonances can be detected at frequencies close to 300 MHz even though the stents are not purposely designed to facilitate such detection. We discuss how stent resonances can be used to monitor restenosis with non-invasive and non-ionizing techniques.A frequency reconfigurable cell for beam-scanning reflectarrayshttp://hdl.handle.net/2117/22467
Title: A frequency reconfigurable cell for beam-scanning reflectarrays
Authors: Rodrigo López, Daniel; Jofre Roca, Lluís; Perruisseau Carrier, Julien
Abstract: Reflectarray antennas are excellent candidates for beam-scanning applications thanks to their low loss, light and quasi-planar structure and ease of electronic control. However, reflectarray antennas suffer from narrower bandwidths than phased arrays and reflector solutions. In this context we present a frequency-reconfigurable cell for beam-scanning reflectarrays, as a solution for applications that operate over a large frequency range but that require a narrower instantaneous bandwidth. The presented cell requires only two switches and one varactor to provide a reflection coefficient with continuously tunable phase over a 270° range which can be shifted over a 40% frequency range.Tue, 01 Apr 2014 12:44:12 GMThttp://hdl.handle.net/2117/224672014-04-01T12:44:12ZRodrigo López, Daniel; Jofre Roca, Lluís; Perruisseau Carrier, JuliennoPlanar antenna arrays, Reflectarray antennasReflectarray antennas are excellent candidates for beam-scanning applications thanks to their low loss, light and quasi-planar structure and ease of electronic control. However, reflectarray antennas suffer from narrower bandwidths than phased arrays and reflector solutions. In this context we present a frequency-reconfigurable cell for beam-scanning reflectarrays, as a solution for applications that operate over a large frequency range but that require a narrower instantaneous bandwidth. The presented cell requires only two switches and one varactor to provide a reflection coefficient with continuously tunable phase over a 270° range which can be shifted over a 40% frequency range.Enhancing RFID sensing capabilities: multi-load backscatteringhttp://hdl.handle.net/2117/22268
Title: Enhancing RFID sensing capabilities: multi-load backscattering
Authors: Capdevila Cascante, Santiago; Jofre Roca, Lluís; Romeu Robert, Jordi; Bolomey, Jean Charles
Abstract: This conference paper presents some experimental results using the concept of an multi-loaded enhanced RFID tag capable of switching between different loads to fully determine the input impedance of the RFID tag antenna which can then be used for sensing applications.Tue, 18 Mar 2014 16:36:19 GMThttp://hdl.handle.net/2117/222682014-03-18T16:36:19ZCapdevila Cascante, Santiago; Jofre Roca, Lluís; Romeu Robert, Jordi; Bolomey, Jean CharlesnoAntenna measurements, Impedance, Impedance measurement, Radiofrequency identification, Temperature measurement, ThermistorsThis conference paper presents some experimental results using the concept of an multi-loaded enhanced RFID tag capable of switching between different loads to fully determine the input impedance of the RFID tag antenna which can then be used for sensing applications.Iterative method of moments solution of problems involving electrically large and concave geometrieshttp://hdl.handle.net/2117/21799
Title: Iterative method of moments solution of problems involving electrically large and concave geometries
Authors: Heldring, Alexander; Rius Casals, Juan Manuel; Úbeda Farré, Eduard
Abstract: This paper presents a study of the scaling with frequency (computational complexity) of preconditioned iterative solution, using the Multilevel Fast Multipole Method, of a class of radiation and scattering problems that exhibits particularly slow convergence: problems involving electrically large, open and concave geometries. A comparison is presented between a well-known state of the art preconditioner (ILU) and a recently introduced preconditioning method, the Multiscale Compressed Block Decomposition.Thu, 27 Feb 2014 18:46:20 GMThttp://hdl.handle.net/2117/217992014-02-27T18:46:20ZHeldring, Alexander; Rius Casals, Juan Manuel; Úbeda Farré, EduardnoAccuracy, Complexity theory, Convergence, Electron tubes, Geometry, Iterative methods, Matrix decompositionThis paper presents a study of the scaling with frequency (computational complexity) of preconditioned iterative solution, using the Multilevel Fast Multipole Method, of a class of radiation and scattering problems that exhibits particularly slow convergence: problems involving electrically large, open and concave geometries. A comparison is presented between a well-known state of the art preconditioner (ILU) and a recently introduced preconditioning method, the Multiscale Compressed Block Decomposition.Volumetric testing for a nonconforming discretization in method of moments of the electric-field surface integral equationhttp://hdl.handle.net/2117/21179
Title: Volumetric testing for a nonconforming discretization in method of moments of the electric-field surface integral equation
Authors: Úbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, Alexander
Abstract: Implementations in Method of Moments of the Electric-Field Integral Equation (EFIE) are traditionally carried out with divergence-conforming sets, with normal continuity of the current across edges. This gives rise to awkward implementations around junctions in composite dielectric objects. Also, RWG-implementations of the Combined-Field Integral Equation for sharp-edged objects suffer from some loss of accuracy. In this paper, we present a new nonconforming discretization of the EFIE, with no continuity requirements across edges. In the generation of the impedance elements, we employ a volumetric testing over a set of tetrahedral elements attached to the meshed surface to let the hyper-singular Kernel contributions numerically manageable. We show that the decomposition of the current into normally-continuous and discontinuous contributions leads to enhanced accuracy in the computed RCS.Wed, 08 Jan 2014 17:33:44 GMThttp://hdl.handle.net/2117/211792014-01-08T17:33:44ZÚbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, AlexandernoDielectrics, Face, Integral equations, Junctions, Method of moments, Surface impedance, TestingImplementations in Method of Moments of the Electric-Field Integral Equation (EFIE) are traditionally carried out with divergence-conforming sets, with normal continuity of the current across edges. This gives rise to awkward implementations around junctions in composite dielectric objects. Also, RWG-implementations of the Combined-Field Integral Equation for sharp-edged objects suffer from some loss of accuracy. In this paper, we present a new nonconforming discretization of the EFIE, with no continuity requirements across edges. In the generation of the impedance elements, we employ a volumetric testing over a set of tetrahedral elements attached to the meshed surface to let the hyper-singular Kernel contributions numerically manageable. We show that the decomposition of the current into normally-continuous and discontinuous contributions leads to enhanced accuracy in the computed RCS.Antenna input impedance measurement using multi-load MSThttp://hdl.handle.net/2117/20324
Title: Antenna input impedance measurement using multi-load MST
Authors: Romeu Robert, Jordi; Capdevila Cascante, Santiago; Bolomey, Jean Charles; Jofre Roca, Lluís
Abstract: This paper presents the practical use of modulated scatterer technique (MST) for the measurement of the antenna input impedance using a multi-load automatic switching device, and it also includes the analysis of the measurement error as a function of the selected loads in the MST circuitry.Mon, 07 Oct 2013 16:16:38 GMThttp://hdl.handle.net/2117/203242013-10-07T16:16:38ZRomeu Robert, Jordi; Capdevila Cascante, Santiago; Bolomey, Jean Charles; Jofre Roca, LluísnoElectric impedance, Electric impedance measurementThis paper presents the practical use of modulated scatterer technique (MST) for the measurement of the antenna input impedance using a multi-load automatic switching device, and it also includes the analysis of the measurement error as a function of the selected loads in the MST circuitry.Preconditioning the Electric Field Integral Equation with the MS-CBD methodhttp://hdl.handle.net/2117/20137
Title: Preconditioning the Electric Field Integral Equation with the MS-CBD method
Authors: Heldring, Alexander; Úbeda Farré, Eduard; Rius Casals, Juan Manuel
Abstract: A novel preconditioning scheme for Method of Moment computations is proposed. It consists of an adapted version of an accelerated direct solution method, the Multiscale Compressed Block Decomposition. It is of particular interest for accelerating the convergence of the iterative solution of open problems that are electrically large and exhibit strong concavity.
For such problems, when solved with the Multilevel Fast Multipole Algorithm, the convergence is the main efficiency
bottleneck. The novel scheme is compared with the de facto
standard preconditioner ILU for a representative problem and shown to be considerably more efficientFri, 13 Sep 2013 14:36:51 GMThttp://hdl.handle.net/2117/201372013-09-13T14:36:51ZHeldring, Alexander; Úbeda Farré, Eduard; Rius Casals, Juan ManuelnoIntegral Equations, Method of Moments, Fast Iterative Methods, PreconditioningA novel preconditioning scheme for Method of Moment computations is proposed. It consists of an adapted version of an accelerated direct solution method, the Multiscale Compressed Block Decomposition. It is of particular interest for accelerating the convergence of the iterative solution of open problems that are electrically large and exhibit strong concavity.
For such problems, when solved with the Multilevel Fast Multipole Algorithm, the convergence is the main efficiency
bottleneck. The novel scheme is compared with the de facto
standard preconditioner ILU for a representative problem and shown to be considerably more efficient